Strength of shields vary with each game.
Minors (Blue) are scrubs that barely move and miss a lot of shots. They should not be underestimated though. Majors (Red) are pros that are constantly on the move and fire in short accurate bursts. They can be more intimidating than most Elites.
White Elites (Ultras)Edit
Ultras in Halo 2 are bastards that rely on raw firepower and cheap parlor tricks, such as sword pull. Basically, piss them off and they pull out a sword. This is a reliable way to get a sword for sword tricks.
Be very careful of dual-wielding Ultras. They are some of the most dangerous enemies in the game.
Jetpack Elites (Rangers)Edit
In Halo 2, Jetpack Elites dual-wield Plasma Rifles. Their shields are weaker than normal Elites.
Invisible Elites (Stealth)Edit
In Halo: CE, Stealth Elites are completely unshielded.
In Halo 2, they have the weakest shields of any Elite, but this is made up for by their uber recharge rate, which makes them extremely durable. Stealth Elites, like all invisible enemies, do not turn the reticule red; therefore, you must de-camo them to use them for sword tricks. Melee attacks are a good way of de-camoing enemies.
Black Elites (Spec Ops)Edit
Spec Ops Elites wear black armor in Halo: CE, and dark purple armor in Halo 2 and 3. They can use Active Camo, although it is scripted and only utilized outside of enemy engagements. They can be seen using the Needler, Beam Rifle, and Energy Sword.
Gold Elites (Zealot)Edit
In Halo: CE, Zealots wield Plasma Rifles or Energy Swords. They have much stronger shields than normal Elites. Their tenacity is unmatched.
Strength of shields vary with each game.
Major Elites in Reach are a red-orange color, not to be confused with the gold armor of Generals.
White Elites (Ultras) in Reach are extremely common, much more so than in Halo 2. On Legendary, they can spawn in groups of 3 or 4. They will occasionally use Armor Lock to tank explosions, such as grenades or needle supercombines. Unlike Halo 2, Ultras in Reach possess no unique berserk, they will run and charge without changing guns like any other Elite.
Gold Elites (Generals) in Reach have the strongest shields of any Elite, even stronger than Zealots. They are also fairly common. They are usually found wielding swords or heavy weapons (FRG/Plasma Launcher/rockets).
Jetpack Elites (Rangers)Edit
In Halo: Reach, Rangers were changed so they can no longer continuously fly. Instead, they perform extended jumps, much like Jump Pack Brutes. They usually use plasma repeaters, needle rifles, concussion rifles or focus rifles.
In Halo 4, they wield carbines or storm rifles.
Invisible Elites (Spec Ops)Edit
The Invisible Elites in Reach are a cross between the Spec Ops and Stealth Elites in earlier games. They have the range of weaponry of a Spec Ops, and weaker shields and constant active camo like a Stealth Elite.
Maroon Elites (Zealots)Edit
In Reach, Zealots are changed to be a maroon/purple color. They appear on the levels Winter Contingency, Tip of the Spear, and The Pillar of Autumn (Halo: Reach). An extra-strong Zealot, the Field Marshal, is encountered on The Pillar of Autumn. He's noticeably faster and more responsive, and carries a primary and secondary gun, fuel rod gun and energy sword respectively.
They're all scrubs except for:
These guys almost always have Needlers and the projectiles will almost always hit you, even when you're behind cover. Don't run, don't hide, just hope.
Spec Ops Grunts (Black)Edit
These guys carry Fuel Rod Guns. In Halo: CE, the FRG will explode shortly after you kill them. In Halo 2, the blast radius is big enough to damage through thin walls e.g. at the second gondola ride on Regret.
In Halo 1, they are simply unpredictable. A shot to their shield arm does not always yield the same reaction. They often do a rolling evasive maneuver when shot at. They are usually the culprits who alert everyone to your location.
In Halo 2/3, they run faster. In Halo 3, they are more evasive as well. In Halo: Reach/4, they are slower and should not be a thing. In these games, shooting them in their shield arm is singlehandedly the best way to expose their head.
In Halo 2 Legendary, these guys are lethal. They have eyes in the back of their heads and can shoot you from anywhere, even if they're not pointing at you.
They can practically tank everything you throw at them, but they fall easily to headshots. And they are very fast.
Often deployed in pairs, they are very slow and easy to anticipate. Usually, they can be avoided. In Halo 2/3, they use a charging beam cannon which is a lot easier to avoid.
In Halo 1, there is an exploit that lets you kill them with one shot from a pistol/sniper rifle.
In Halo 2, a common tactic is to stick a Hunter, causing it to turn around and expose it's back.
In Halo 3, there's often a power weapon nearby. You can also use all your stickies and hope it kills one. Hunters in Halo 3 are suspectible to the Spiker and Fuel Rod Gun. The Gravity Hammer is only effective against them on lower difficulties.
In Reach, they are massive bullet sponges and their fuel rods have a larger blast radius, keep your distance.
In Halo 4, they are scrubs.
Watch out for the ones with Needlers.
Brutes are notoriously imbecilic AI.
In Halo 2, Brutes often have screwed up pathfinding; this sometimes leads to them endlessly running into boxes and the like. If you think you've killed everything, there's no movement on radar, and yet something isn't triggering, a braindead Brute running into a box is the likely culprit.
In Halo 3, Brutes have a chance to berserk when their armor breaks. Brute drivers are known for driving off ledges and splattering their comrades. It's not uncommon for one to suicide with a grenade. When they berserk, they will run around wildly, slowly.
In Halo: Reach, killing one Brute after another often triggers a chain reaction of berserking. Imagine the Brutes as operating in pairs, like H2/H3 Hunters. Brutes in Reach are known for sticking their comrades and charging at players in an unconvincing manner (e.g. compared to H2/H3, where they wildly run about) when their partner has been killed.
Brute Minors are unarmored in Halo 2. They wield Carbines or Brute Plasma Rifles.
In Halo 3 & ODST, Minors have turquoise/teal armor, with helmets. They wield Spikers, Carbines and Plasma Rifles. Majors wear power armor. The noob combo works well. Brute Ultras wear indigo armor, and can carry Beam Rifles and pilot Choppers and Prowlers.
(needs more info about equipment drops)
In Halo 2, Captains are the ones with the helmet and the flag on their back. They usually wield Brute Shots, but sometimes Brute Plasmas, Carbines, or Shotguns (as in The Great Journey).
In Halo 3 & ODST, Captains wear blue-purple armor and wield Brute Shots, Spikers or Plasma Rifles. They also carry equipment. (more detail needed) Captain Majors wear gold. Captain Ultras wear cobalt.
Chieftains & BodyguardsEdit
Chieftains wield Gravity Hammers. Tartarus is the only Chieftain in Halo 2. They are more common in Halo 3 & ODST. They are often equipped with extremely advantageous armor, but up close, they're not much different from any other Brute. Close the distance when you can, it'll save you some ammo. Chieftains possess an unique berserk, which can only be seen after they use their Invincibility. It grants them the ability to jump at players.
Bodyguards are found in the company of Chieftains, and often use Regenerators. They wear sky blue armor.
Jump Pack BrutesEdit
In Halo 3 & ODST.
In Halo 3 & ODST. Stalkers usually wield Plasma Rifles. Often they stand in place and fire away, so having a Beam Rifle with you is ideal.
In Halo 1, it could be argued that they are in their prime. You can use them to get to a higher spot, substituting a grenade jump. Halo 1 is infamous for the Flood buddy glitch, which are combat forms that can serve as bodyguards once their whip arm has been detached.
In Halo 2, they are really fast and do devastating damage to you and your allies. They can carry swords and their rockets home in on you. And they now drive/operate vehicles.
In Halo 3, they are annoying.
Infection Forms ("Popcorn")Edit
In Halo 1, you usually encounter large crowds of them. When one popcorn Flood dies, it will often take out a bunch of others with it's death explosion. Meleeing them is very viable in this game and is easily a good alternative to shooting them (which might draw unwanted attention).
In Halo 2, they are singlehandedly the most devastating Flood unit. Just one of these are enough to kill you if given the chance. Normally, they jump at you, do some damage, and pop, but there is a glitch where they don't die upon attack.
In Halo 3, they generally stay out of combat when there's plenty of Combat Forms in the vincinity. They can raise dead Flood bodies and can enter the dead bodies of the deceased, converting them into Flood.
In Halo 1, they're encountered in droves and are plain awesome, charging at you like fucking athletes and often serving as the catalyst for explosive chain reactions.
In Halo 2, they are extremely slow but their death explosions can be devastating and the Infection Forms they bring forth can easily wipe you out.
In Halo 3, they are fat, slow, and worthless.
Knights often use Suppressors and LightRifles. They are capable of teleporting and have a fast shield recharge rate. They often use teleport to give their shields time to recharge. They lack a visual cue for shield damage unlike Elites. They are also harder to exploit in close combat. They can deploy Watchers from their carapace, although this is usually scripted. Knights can come in three forms.
Knight Lancers are similar to normal Knights, but they are more likely to abuse teleport. They possess a distinctive zig-zag charge attack, which is very predictable, avoidable, and is rarely used.
Knight Battlewagons have orange spikes on their back. They are similar to normal Knights, but they are harder to approach due to their Scattershot. Besides that, the only thing you have to worry about is their unique jump attack, which is also rarely used.
Knight Commanders are fiery in appearance and almost always have an Incineration Cannon. They possess an overpowered explosive jump which can be devastating.
They should have been called Wretched. Imagine every Drone/Engineer having a fast recharging shield, massive bundles of health, a spammable gun (that everyone generally hates), the ability to defend each other, produce a dozen Grunts out of thin air, and deflect grenades thrown at them or their allies. Then imagine them having a ridiculously small and peculiar hitbox, being able to move at the speed of light, and fleeing from every goddamn battle. Also consider the possibility of a single Knight spewing dozens of these from it's back like some kind of fucking mobile factory. Oh, and these guys can resurrect their dead commanders. They will swarm you at every waking moment; cover is rarely an option so keep your distance when you can. They are very spammable, although this is underutilized in Campaign (thank God).
Basically, they are pure evil and should be prioritized first. And don't forget to hate them, they will supersede every enemy in the annoying category. They will aggro you, throw you into despair, and cause you to lose a lot of speed.
Fortunately, their devotion to their commanders oh so often puts them in jeopardy. Sometimes, all you have do is kill a single Knight and every Watcher in the vincinity will naively vie for the task of resurrection, becoming extremely vulnerable. It's very easy to sprint/jetpack past when there's only a few of them flying around. Some Watchers will spawn with a scripted task in mind e.g. spawn a Promethean turret, giving you ample amount of time to engage or run past them. Also, if you have an automatic weapon, you can send them packing with a few bursts, giving you enough time to take out a bunch of Crawlers or a Knight. They can be quickly taken out with ranged precision rifles, especially snipers. With the main rifles, it only takes 3-5 precise shots to their eye, which is fucking small. Goddamn it
Skirmisher reincarnate, but generally a lot less damage spongy and more inclined to stay in one spot. They are arguably the only well-balanced Promethean enemy.